Mixed esters of lower and higher fatty acids and process of making same



Patented Oct. 20, 1925.

. UNITED STATES PATENT OFFICE.

enonen L. scnwanrz, or wnmmoron, nmawann, assmnon do n I. no mm m:

Nnuouns a comramr, or WILMINGTON, nnnawann, a conrona'non or 1mmwarm.

.. m'xnn ns'rnns or Lownn AND manna FATTY aczns an rnocnss or mum sum.

No Drawing. Application flied To all whom) it may concern:

Be it 'knownt-hatI, GEORGE L. SCHWARTZ,

a citizen of the United States, and a resident of \Vilmington, in the county of New Castle 6 and State of Delaware, have invented cer-' tain new and useful Mixed Esters of Lower and Higher Fatty Acids and Processes of Making Same, of which the following is a specification. i

This invention relates to mixed esters of the lower and higher fatty acids, and particularly to the mixed glycerides of coconut oil acids and acetic acid, and comprises, as new products, mixed esters of this kind having certain characteristics as hereinafter defined, and a process of making said products.

These new mixed esters are to be used primarily as softeners of pyrox lin, especially inconnection with the manufacture of arti- 2 ficial leather. The vegetable oils have long been used as softeners of pyroxylin, and in particular castor oil and blown rapeseed oil lave been used. Both of these oils'are glycerides of unsaturated fatty acids. Their iodine numbers are high, and probably as a result of this unsaturated condition they are subject to certain physical or chemical changes. For example, castor oil readily be coni'srancid when exposed in a pyroxylin film, and it gradually undergoes oxidation which-causes a hardening of the film. Practically the only low melting vegetable oil that does not have a high iodine number is coconut oil. This oil is available in large quantities and would be an excellent softener of pyroxylin if its melting point were somewhat lower. It is much less subject to rancidity development and to gradual oxidation than oils now used, because the percentage of unsaturated glycerides which it contains is very low. One object, therefore, of my invention is to reduce the melting "point of coconut oil so as to make it a better softener of pyrox-ylin.

Another object of my invention is to impart .some solvent power for pyroxylin to coconut oil. I have found that it is often desirable to use as a softener a substance which has mild. solvent power for pyroxylin.

April 11, 1922. Serial No. 551,734.

All of the known vegetable oils are practically without solvent action on pyroxylin,

and it has heretofore been thought necessary,

if .solvent power was required, to add a sol-- ing point is sometimes quite marked; Commercial coconut oil, for example, has a freezing point of from l l to 22 0., whereas, after the introduction of an acetyl grou inform -a mixed ester, the melting point 1s usually between 5 and l3 C., the exact value dependin'g'upon the extent to which the acetyl group has displaced higher fatty acid radicals in the glycerides present. 'In general a mixed glyceride made in accordance with my invention should have a freezing point below 10 C., especially where the mixed glyceride is to be used as a softener of pyroxylin, although in .some cases the increase in solvent power attending the intro duction of a lower fatty acid radical may be so' great as to render the lyceride suitable as a softener even though the freezing point thereof be substantially above 10 C.

The expression lower fatty acid is used herein to mean either formic, acetic, or propionic, acid; and the expression higher fatty acid has reference to acids of the aliphat ic series containing more than nine carbon atoms. The alcohol radical of the mixed ester may be the radical of any one of various olyhydric alcohols, and es ecially of the ower polyhydric alcohols having between one and four hydroxyl principal members of this class ing lyceiiol and ethylene, propylene, and buty ene, g yco s. Y

Where the new product has been obtained by the action of acetic acid "on coconut oil, of which the chief constituent is the glyceride of Iauric acid, the new product will ups, the

consist of a mixture of mixed esters of which. the major part will be acetyl-laurins, with acetyl-palmitin and aoetyl-myristin present in small proportions. The mono-acet l-la-urin formed has probably the fol owing graphical formula:

- lows 1. Glycerine, glacial acetic acid and coconut oil acids are heated at a relatively low temperature until the mixture of mono-, di-

- and triacetins is formed in equilibrium with the acetic acid. Then the excess acetic acid is distilled off, the temperature is raised to ISO-200 C. and heating is continued until all but about 1% of the coconut oil acids are neutralized (esterified), using a stream of nitrogen to sweep out water as formed.

2. To the ingredients in (1) a small amount of sulfuric acid is added as a catalyst and the same procedure is followed except that the hi hest temperature of heatin is 170 and t e product after practica neutralization is washed with Water to remove sulfuric acid.

3. The same ingredients and method are used as in-'(2) except that the sulfuric acid is neutralized with sodium acetate after the heatin period at a low temperature.

4. oconut oil and glacial acetic acid are heated under pressure until the r uisite amount of, coconut oil acids are disp aced, free acetic acid is then distilled off and the free coconut oil acids are neutralized with diacetin,- diacetin and g1 cerine, or a crude mixture of mono-, dian triacetins by heating at ISO-200 C. with a stream of nitro gen to remove water as formed.

5. Coconut oil, glacial acetio' acid and a small amount of sulfuric acid are heated at a relatively low temperature until a suflicient amount of .coconut oil acids has been re laced by acetic acid. Glycerine-is then a ded and heating at a relatively low temcomplete.

6. Coconut oil, glacial acetic acid, glycer inc and a small amount-of sulfuric acid are treated as in (5) except that no further addition of glycerine is made.

7. Coconut oil and triacetin are heated at ISO-200 C. I j

8. Coconut oil, triacetin and a small amount of sulfuric acid are heated together at 150170 C. until equilibrium is established, whereupon the sulfuric acid is washed out with water.

Method (2) is at present believed to' be most satisfactory, taking into consideration time, materials cost and quality-of product, so for this reason I shall of method (2) in detail.

The following ingredients are mixed in.

out the remaining heating period. A stream of nitrogen is passed through the mixture throughout this latter heating stage to sweep out water as formed. After neutralization is practically complete the crude product is washed with an aqueous sodium chloride solutio to remove sulfuric acid. The washe product is then heated for two hours on a steam bath with 2% of its weight of decolorizing carbon and is filtered. The finished product obtained by carrying out this process on a small scale was a light brown, transparent, oily liquid with a slight odor resembling coconut. oil and freezing at 10 to 11 C. It contained 1.03% free coconut oil acids. The yield was 87.2% of the, theoretical. The finished product is miscible in all proportions in mineral oil; it colloids pyroxylin at normal temperatures; and it does not become rancid.

A mixture of mixed glycerides prepared by any of the above methods is practically non-volatile and cannotbe distilled at pressures as low as 14 mm. without partial decomposition. This product consists of a mixture of all the possible glycerides of acetic acid and coconut oil acids, ranging from some triacetin through the mixed glycerides to and including some coconut oil. Thefreezin point varies according to the ratio of acety to coconut oil acid groups and usually falls within the range of 5 to 13 C.

I have referred above to sulfuric acid as the catalyst but there is no doubt that various other mineral acids will have the same give an example water 967 parts .(by weight), glacialaction, though varying in degree. I The -tem perature range for esterification has been given as above 150 C. but it is probable that esterification of the coconut oil-acids stituted by chemical equiva ents .of crude acetin mixtures which are obtained by heat ing glycerine and glacial acetic acid with or without a- ,catalyst at the boiling point of acetic acid in the mixture until equilib- .rium has been reached between the acetins and acetic acid.

The coconut oil acids that I have used were obtained by hydrolysis ofcommerclal coconut oil, with subsequent distillation under reduced pressure.

Although in "the above description of methods of making the new acetyl derivatives, Ihave referred to the use of glacial acetic acid, it will be understood that acetic acid of a concentration lower than what is signified by the word glacial may be used.

Coconut oil, as has been indicated above, is the oil with which I prefer to start, but other materials may'with advantage beconverted into acetyl-glycerides'in themanner above described, as, for example, commercial stearic acid, which contains a large proprtion of pahn'itic acid, or palm kernel oil, or the acids of this oil.

Th'e'new products, when obtainedfrom oils such as coconut oil, may be defined generically as mixtures of acetyl derivatives of glycerides of two or more higher fatty acids each having from 10 to 16 carbon atoms. The glyceride mixture prepared in accordance with the above examples will contain a substantial proportion of dia-,

cetyl-glycerides of the higher fatty acids, as, for example, diacetyl-laurin, diacetyl-myristin, and diacetyl-palmitin. The molecular structure of the alpha-gamma-diaeetyllaurin, which is typical, is probably as follows:

, mo-o-co-cn.

n c-o-co-wnaio-cm n,c-o-oo-cH.-

. cetyl derivative, the algha-beta-diacetyl derivatlve is believed-to e z in minor proportions.

formed, although An approximate idea of therelative proportions of the mixed esters of the various glycerides obtained by my process, may be gained from the following showing the relative proportions of combinedfatt acids which are present in coconutoil: aproic 6 12 2) p y 8 18 2) 0.25%, capric (C 'H O 19.5%, lauric 12 24 2) 400%, mynstlo u as z 24.0%, palmitic (C H O 10.6%, olelc 18 3402) l A decidedly greater lowering of the freezing point and increase in solvent power of the higher fatty acid glycerides is attained by introducing two, instead of'merely one,

acetylgroupinto the glyceride molecules.

My invention includes broadly the diacetyl-mono-acyl-glycerides, where acyl is used to mean the acid radical of a higher fatty acid, as well as corresponding glycerides containing two fomyl or two propionyl groups.

I claim: 1. The process of-producing a composition, containing mixed glycerides oflower and higher fatty acids which comprises heating the glyceride of a higher fatty acid glycerine, heating the resulting mass at a temperature substantially below 150 C. until a crude acetin mixture is formed, distillingofi any excess acetic acid, and'then heating the resulting mixture at a tempera- 1 ture above 150 C(but below that at which trated acetic acid in the presence of an 'es--' terification catalyst untilthe desired proportion of coconut oil acidradicals hav'e'been replaced by acetic acid radicals in the glycerides of said oil, adding glycerine, heating the resulting mass at a temperature substan-" tially below 150- C. until a crude acetin mixture'is formed, distilling ofl any excess acetic acid, and then heating the resulting mixture at a temperature of from about 150 to 170 0.,- while passing an inert gas through the mixture to remove water as it is formed, until esterification of coconut oil acids by the acetin is practically complete. 3. A composltlon of.matter comprising a mixed ester of a lower and a saturated high- .er fatty acid, the alcohol radical of said ester being that of a polyhydric alcohol having between'l and 4 hydroxylgroups, said cramppsition having afreezing point below 1 O I 4. A composition of matter comprising mixed esters of a lower fatty acid and at least-two higher fatty acids each havin from 12 to 16 carbon atoms, the alcohol ra two lower-fatty-acid radicals and one higher fatty acid radical having from 10 to 16 carbon atoms.

7. A compositionof matter comprising a mixed g1 ceride whose molecules contailn two acety radicals and one saturated higher fattyacid radical. 1

.8. A composition of matter comprising a mixed glyceride whose molecules contain two acetyl radicals and one higher fatty acid radical having from 10 to 16 carbon atoms.

9. A composition of matter comprising diacetyl-laurm. I

10. A'composition of matter comprising a mixed glyceride whose molecules contain two acetyl radicals and one higher fatty acid radical, and a mixed glyceride whose molecules contain two acetyl radicals and one radicalof another higher fatty acid, the

freezing int of said composition being below 10 11. A com osition of matter comprising a mixed glycerlde whose molecules contain two acetyl radicals and one higher'fatty acidradical, and a mixed glyceride whose moleculcs contain two acet l radicals and one radical of another'hig er fatty acid, each of said higher fatty a'cid'radicals having from 10 to 16 carbon atoms, the freezin point of said composition being below 10 12. A composition of matter comprisin an acetyl-glyceride of a higher fatty aci said glyceride containing at least one acetyl group and a diacetyl-glyceride' of a higher fatty acid.

13. A composition of matter comprisin an acetyl-glyceride of a higher fatty aci having from 10 to 16 carbon atoms, said glyceride containing at least one acetyl group, and a diacetyl-glyceride of a higher fatty acid having from 10 to 16 carbon atoms.

14. A composition of matter comprising a mixed ester of a lower fatty acid and lauric acid, the alcohol radical of said ester being that of a polyhydric alcohol, having between 1 and 4 hydroxyl groups.

15. A composition of matter comprising a mixed ester of a lower fatt acid and lauric acid, the alcohol radical 0 said ester being that of a olyhydric alcohol, having between."

mixed ester of a lower fatty acid, lauric acid, and at least one other higher fatty acid, the alcohol radical of said ester being that of a polyhydric alcoholhaving between 1 and 4 hydroxyl groups.

17. A composition of matter as set forth in claim 16 in which the composition has a freezing oint below 10 C.

In testimony whereof I aflix my signature.

GEORGE L. SCHWARTZ. 

